Cov nyhuv ntawm cellulose ether ntawm tshav kub ntawm hydration ntawm cov cement sib txawv thiab ib qho ore

Cov teebmeem ntawm cellulose ether ntawm cov dej kub ntawm Portland cement, sulfoaluminate cement, tricalcium silicate thiab tricalcium aluminate hauv 72h tau muab piv los ntawm isothermal calorimetry test. Cov txiaj ntsig tau pom tias cellulose ether tuaj yeem txo cov dej thiab cov cua kub tso tawm ntawm Portland cement thiab tricalcium silicate, thiab txo cov nyhuv ntawm hydration thiab kub tso tawm ntawm tricalcium silicate yog qhov tseem ceeb dua. Cov nyhuv ntawm cellulose ether ntawm kev txo cov cua sov tso tawm ntawm hydration ntawm sulfoaluminate cement yog qhov tsis muaj zog, tab sis nws muaj qhov tsis muaj zog ntawm kev txhim kho lub tshav kub tso tawm ntawm hydration ntawm tricalcium aluminate. Cellulose ether yuav adsorbed los ntawm ib co hydration khoom, yog li ncua lub crystallization ntawm hydration khoom, thiab ces cuam tshuam lub hydration tshav kub tso tus nqi ntawm cement thiab ib ore.

Cov lus tseem ceeb:cellulose ether; cement; Ib leeg ore; Thaum tshav kub kub hydration; adsorption

1. Taw qhia

Cellulose ether yog ib qho tseem ceeb thickening tus neeg saib xyuas thiab cov dej tuav tus neeg sawv cev nyob rau hauv qhuav sib tov mortar, nws tus kheej-compacting pob zeb thiab lwm yam tshiab cement-based cov ntaub ntawv. Txawm li cas los xij, cellulose ether tseem yuav ncua sijhawm cov cement hydration, uas yog qhov tsim nyog los txhim kho lub sijhawm ua haujlwm ntawm cov khoom siv cement, txhim kho mortar sib xws thiab cov pob zeb tawg lub sij hawm poob, tab sis kuj yuav ncua kev tsim kho. Tshwj xeeb, nws yuav muaj kev cuam tshuam tsis zoo rau mortar thiab pob zeb siv nyob rau hauv qhov kub thiab txias ib puag ncig. Yog li ntawd, nws tseem ceeb heev kom nkag siab txog txoj cai ntawm cellulose ether ntawm cement hydration kinetics.

OU thiab Pourchez systematically kawm txog cov teebmeem ntawm molecular tsis xws li molecular hnyav ntawm cellulose ether, hom hloov los yog degree ntawm kev hloov ntawm cement hydration kinetics, thiab kos ntau cov lus xaus: Lub peev xwm ntawm hydroxyethyl cellulose ether (HEC) kom ncua lub hydration ntawm cement feem ntau muaj zog dua li ntawm methyl cellulose ether (HPMC), hydroxymethyl ethyl cellulose ether (HEMC) thiab methyl cellulose ether (MC). Hauv cov cellulose ether uas muaj methyl, qhov qis dua cov ntsiab lus methyl, lub zog muaj peev xwm ncua kev hydration ntawm cement; Qhov qis dua qhov hnyav molecular ntawm cellulose ether, lub zog muaj peev xwm ncua kev hydration ntawm cement. Cov lus xaus no muab kev tshawb fawb hauv paus rau kev xaiv cellulose ether kom raug.

Rau cov khoom sib txawv ntawm cov cement, cov nyhuv ntawm cellulose ether ntawm cov cement hydration kinetics kuj yog ib qho teeb meem txhawj xeeb heev hauv kev siv engineering. Txawm li cas los xij, tsis muaj kev tshawb fawb txog qhov no. Hauv daim ntawv no, kev cuam tshuam ntawm cellulose ether ntawm hydration kinetics ntawm Portland cement, C3S (tricalcium silicate), C3A (tricalcium aluminate) thiab sulfoaluminate cement (SAC) tau kawm los ntawm isothermal calorimetry test, kom nkag siab ntxiv txog kev sib cuam tshuam thiab Internal mechanism ntawm cellulose ether thiab cement hydration khoom. Nws muab cov hauv paus kev tshawb fawb ntxiv rau kev siv cov cellulose ether hauv cov khoom siv cement thiab tseem muab kev tshawb fawb hauv paus rau kev sib cuam tshuam ntawm lwm cov khoom sib xyaw thiab cov khoom siv cement hydration.

2. Kev xeem

2.1 Cov khoom siv raw

(1) Portland cement zoo tib yam (P·0). Tsim los ntawm Wuhan Huaxin Cement Co., LTD., qhov tshwj xeeb yog P· 042.5 (GB 175-2007), txiav txim siab los ntawm wavelength dispersion-hom X-ray fluorescence spectrometer (AXIOS advanced, PANalytical Co., LTD.). Raws li kev soj ntsuam ntawm JADE 5.0 software, ntxiv rau cov cement clinker minerals C3S, C2s, C3A, C4AF thiab gypsum, cement raw cov ntaub ntawv kuj suav nrog calcium carbonate.

(2) sulfoaluminate cement (SAC). Lub zog ceev sulfoaluminate cement tsim los ntawm Zhengzhou Wang Lou Cement Industry Co., Ltd. yog R.Star 42.5 (GB 20472-2006). Nws cov pab pawg tseem ceeb yog calcium sulfoaluminate thiab dicalcium silicate.

(3) tricalcium silicate (C3S). Xovxwm Ca (OH) 2, SiO2, Co2O3 thiab H2O ntawm 3: 1: 0.08: Ib qho piv txwv loj ntawm 10 tau muab sib xyaw sib xyaw thiab nias nyob rau hauv qhov siab ntawm 60MPa los ua cylindrical ntsuab billet. Lub billet tau calcined ntawm 1400 ℃ rau 1.5 ~ 2 h nyob rau hauv ib tug silicon-molybdenum pas nrig kub hluav taws xob rauv, thiab ces tsiv mus nyob rau hauv lub microwave qhov cub rau ntxiv microwave cua sov rau 40min. Tom qab tshem tawm cov billet, nws tau txias txias thiab rov ua dua thiab calcined kom txog thaum cov ntsiab lus ntawm CaO dawb hauv cov khoom tiav yog tsawg dua 1.0%.

(4) tricalcium aluminate (c3A). CaO thiab A12O3 tau sib tov sib npaug, calcined ntawm 1450 ℃ rau 4 h hauv silicon-molybdenum pas nrig hluav taws xob rauv, hauv av rau hauv cov hmoov, thiab rov qab calcined kom txog thaum cov ntsiab lus ntawm CaO dawb yog tsawg dua 1.0%, thiab lub ncov ntawm C12A7 thiab CA yog tsis quav ntsej.

(5) cellulose ether. Cov hauj lwm yav dhau los piv rau cov teebmeem ntawm 16 hom cellulose ethers ntawm hydration thiab tshav kub tso tus nqi ntawm Portland cement zoo tib yam, thiab pom tias ntau hom cellulose ethers muaj qhov sib txawv tseem ceeb ntawm hydration thiab tshav kub tso cai ntawm cement, thiab soj ntsuam cov txheej txheem sab hauv. ntawm qhov sib txawv tseem ceeb no. Raws li cov txiaj ntsig ntawm kev tshawb fawb yav dhau los, peb hom cellulose ether uas muaj kev cuam tshuam pom tseeb ntawm Portland cement tau raug xaiv. Cov no suav nrog hydroxyethyl cellulose ether (HEC), hydroxypropyl methyl cellulose ether (HPMC), thiab hydroxyethyl methyl cellulose ether (HEMC). Lub viscosity ntawm cellulose ether yog ntsuas los ntawm ib tug teb viscometer nrog ib tug xeem concentration ntawm 2%, ib tug kub ntawm 20 ℃ thiab ib tug kev sib hloov ceev ntawm 12 r / min. Lub viscosity ntawm cellulose ether yog ntsuas los ntawm ib tug teb viscometer nrog ib tug xeem concentration ntawm 2%, ib tug kub ntawm 20 ℃ thiab ib tug kev sib hloov ceev ntawm 12 r / min. Cov molar hloov qib ntawm cellulose ether yog muab los ntawm cov chaw tsim khoom.

(6) Dej. Siv cov dej distilled thib ob.

2.2 Test method

Thaum tshav kub kub hydration. TAM Cua 8-channel isothermal calorimeter tsim los ntawm TA Instrument Company tau txais yuav. Tag nrho cov ntaub ntawv raw tau khaws cia qhov kub thiab txias (xws li (20 ± 0.5) ℃) ua ntej kev sim. Ua ntej, 3 g MAAs thiab 18 mg cellulose ether hmoov tau ntxiv rau hauv calorimeter (qhov loj ntawm cellulose ether rau cov khoom siv ceemellative yog 0.6%). Tom qab kev sib tov tag nrho, cov dej sib xyaw (dej distilled thib ob) tau ntxiv raws li qhov ntsuas dej-cement piv thiab sib tov sib npaug. Tom qab ntawd, nws tau muab tso rau hauv lub calorimeter sai sai rau kev sim. Cov dej-binder piv ntawm c3A yog 1.1, thiab dej-binder piv ntawm lwm yam peb cementitious cov ntaub ntawv yog 0.45.

3. Cov txiaj ntsig thiab kev sib tham

3.1 Cov qhab nia xeem

Cov teebmeem ntawm HEC, HPMC thiab HEMC ntawm hydration heat release rate thiab cumulative heat release rate of dog dig Portland cement, C3S thiab C3A hauv 72 h, thiab cov teebmeem ntawm HEC ntawm hydration heat release rate thiab cumulative heat release rate of sulfoaluminate cement. nyob rau hauv 72 h, HEC yog cov cellulose ether nrog lub zog ncua kev cuam tshuam ntawm hydration ntawm lwm cov cement thiab ib qho ore. Ua ke ob qho kev cuam tshuam, nws tuaj yeem pom tau tias nrog kev hloov pauv ntawm cov khoom siv cementitious, cellulose ether muaj qhov sib txawv ntawm hydration heat release rate thiab cumulative heat release. Kev xaiv cellulose ether tuaj yeem txo cov dej thiab cov cua kub tso tawm ntawm Portland cement thiab C, S, feem ntau ua rau lub sij hawm induction lub sij hawm ncua, ncua cov tsos ntawm hydration thiab kub tso tawm ncov, uas cov cellulose ether rau C, S hydration thiab Thaum tshav kub kub tso tawm qeeb qeeb yog pom tseeb dua li Portland cement hydration thiab kub tso tawm tus nqi ncua; Cellulose ether tuaj yeem ncua lub tshav kub tso tawm ntawm sulfoaluminate cement hydration, tab sis lub peev xwm ncua tsis muaj zog, thiab feem ntau ncua cov dej tom qab 2 h; Rau lub tshav kub tso tawm ntawm C3A hydration, cellulose ether muaj zog accelerating tsis muaj zog.

3.2 Kev tshuaj xyuas thiab kev sib tham

Lub mechanism ntawm cellulosic ether ncua cement hydration. Silva et al. hypothesized tias cellulosic ether nce viscosity ntawm pore tov thiab hindered tus nqi ntawm ionic zog, yog li ncua cov cement hydration. Txawm li cas los xij, ntau cov ntaub ntawv tau ua xyem xyav qhov kev xav no, raws li lawv cov kev sim tau pom tias cellulose ethers nrog qis viscosity muaj peev xwm ua kom cov cement hydration. Qhov tseeb, lub sij hawm ntawm ion txav los yog tsiv teb tsaws yog luv heev uas nws pom tseeb tsis piv rau lub sij hawm ntawm cov cement hydration ncua. Lub adsorption ntawm cellulose ether thiab cement hydration khoom yog suav tias yog qhov laj thawj tiag tiag rau kev ncua ntawm cov cement hydration los ntawm cellulose ether. Cellulose ether tau yooj yim adsorbed rau saum npoo ntawm cov khoom siv dej xws li calcium hydroxide, CSH gel thiab calcium aluminate hydrate, tab sis nws tsis yooj yim rau adsorbed los ntawm ettringite thiab unhydrated theem, thiab lub peev xwm adsorption ntawm cellulose ether ntawm calcium hydroxide yog siab dua. uas CSH gel. Yog li ntawd, rau cov khoom lag luam Portland cement hydration zoo tib yam, cellulose ether muaj lub zog qeeb tshaj plaws ntawm calcium hydroxide, lub zog qeeb ntawm calcium, qhov thib ob ncua ntawm CSH gel, thiab lub zog qeeb tshaj plaws ntawm ettringite.

Cov kev tshawb fawb yav dhau los tau pom tias qhov adsorption ntawm non-ionic polysaccharide thiab cov ntxhia theem feem ntau suav nrog hydrogen bonding thiab tshuaj complexation, thiab ob qhov teebmeem no tshwm sim ntawm pawg hydroxyl ntawm polysaccharide thiab cov hlau hydroxide ntawm cov pob zeb hauv av. Liu et al. Ntxiv rau qhov adsorption ntawm polysaccharides thiab hlau hydroxides raws li acid-base kev sib cuam tshuam, nrog polysaccharides li acids thiab hlau hydroxides ua bases. Rau ib tug muab polysaccharide, alkalinity ntawm cov pob zeb hauv av txiav txim lub zog ntawm kev sib cuam tshuam ntawm polysaccharides thiab minerals. Ntawm plaub lub ntsiab lus gelling tau kawm hauv daim ntawv no, cov hlau tseem ceeb lossis cov hlau tsis muaj xws li Ca, Al thiab Si. Raws li qhov kev txiav txim ntawm cov hlau ua haujlwm, alkalinity ntawm lawv cov hydroxides yog Ca(OH)2>Al(OH3>Si(OH)4. Qhov tseeb, Si(OH)4 kua yog acidic thiab tsis adsorb cellulose ether. Cov ntsiab lus ntawm Ca(OH)2 nyob rau saum npoo ntawm cov cement hydration khoom txiav txim siab lub peev xwm adsorption ntawm hydration khoom thiab cellulose ether Vim calcium hydroxide, CSH gel (3CaO·2SiO2·3H20), ettringite (3CaO·Al2O3·3CaSO4·32H2O). thiab calcium aluminate hydrate (3CaO·Al2O3·6H2O) nyob rau hauv cov ntsiab lus ntawm inorganic oxides ntawm CaO yog 100%, 58.33%, 49.56% thiab 62 .2%. aluminate> CSH gel> ettringite, uas yog raws li cov txiaj ntsig hauv cov ntaub ntawv.

Cov khoom hydration ntawm c3S feem ntau suav nrog Ca (OH) thiab csH gel, thiab cellulose ether muaj qhov cuam tshuam zoo rau lawv. Yog li, cellulose ether muaj qhov pom tseeb qeeb ntawm C3s hydration. Dhau li ntawm c3S, Portland cement zoo tib yam kuj suav nrog C2s hydration uas qeeb dua, uas ua rau cov nyhuv qeeb ntawm cellulose ether tsis pom tseeb nyob rau theem pib. Cov khoom hydration ntawm cov silicate zoo tib yam kuj muaj xws li ettringite, thiab cov nyhuv qeeb ntawm cellulose ether tsis zoo. Yog li ntawd, lub peev xwm qeeb ntawm cellulose ether rau c3s muaj zog dua li ntawm Portland cement zoo tib yam tau pom hauv qhov kev sim.

C3A yuav yaj thiab hydrate sai thaum nws ntsib dej, thiab cov khoom hydration feem ntau yog C2AH8 thiab c4AH13, thiab cov cua kub ntawm hydration yuav raug tso tawm. Thaum cov tshuaj C2AH8 thiab c4AH13 mus txog saturation, crystallization ntawm C2AH8 thiab C4AH13 hexagonal sheet hydrate yuav tsim, thiab cov tshuaj tiv thaiv tus nqi thiab kub ntawm hydration yuav raug txo nyob rau tib lub sij hawm. Vim lub adsorption ntawm cellulose ether rau saum npoo ntawm calcium aluminate hydrate (CxAHy), lub xub ntiag ntawm cellulose ether yuav ncua lub crystallization ntawm C2AH8 thiab C4AH13 hexagonal-phaj hydrate, uas ua rau txo cov tshuaj tiv thaiv tus nqi thiab hydration thaum tshav kub kub tso tawm npaum li ntawd. ntawm ntshiab C3A, uas qhia tau hais tias cellulose ether muaj ib tug qaug zog acceleration muaj peev xwm rau C3A hydration. Nws yog ib nqi sau cia hais tias nyob rau hauv qhov kev ntsuam xyuas no, cellulose ether muaj ib tug tsis muaj zog accelerating muaj peev xwm mus rau lub hydration ntawm ntshiab c3A. Txawm li cas los xij, hauv Portland cement zoo tib yam, vim tias c3A yuav hnov ​​​​mob nrog gypsum los ua ettringite, vim yog lub zog ntawm ca2 + tshuav nyiaj li cas hauv cov kua slurry, cellulose ether yuav ncua kev tsim ntawm ettringite, yog li ncua lub hydration ntawm c3A.

Los ntawm cov teebmeem ntawm HEC, HPMC thiab HEMC ntawm hydration thiab kub tso tawm tus nqi thiab cumulative tshav kub tso tawm ntawm Portland cement zoo tib yam, C3S thiab C3A nyob rau hauv 72 h, thiab cov teebmeem ntawm HEC ntawm hydration thiab kub tso tawm tus nqi thiab cumulative tshav kub tso tawm sulfoaluminate. cement nyob rau hauv 72 h, nws tuaj yeem pom tau tias ntawm peb lub cellulose ethers xaiv, Lub peev xwm ntawm ncua dej ntawm c3s thiab Portland cement yog qhov muaj zog tshaj plaws hauv HEC, ua raws li HEMC, thiab tsis muaj zog tshaj hauv HPMC. Raws li C3A muaj kev txhawj xeeb, peb lub cellulose ethers muaj peev xwm ua kom cov dej ntws tawm kuj yog tib yam, uas yog, HEC yog qhov muaj zog tshaj plaws, HEMC yog qhov thib ob, HPMC yog qhov tsis muaj zog thiab muaj zog tshaj plaws. Qhov no tau lees paub tias cellulose ether tau ncua kev tsim cov khoom hydration ntawm cov ntaub ntawv gelling.

Lub ntsiab hydration khoom ntawm sulfoaluminate cement yog ettringite thiab Al (OH) 3 gel. C2S nyob rau hauv sulfoaluminate cement kuj tseem hydrate sib cais los ua Ca(OH)2 thiab cSH gel. Vim tias qhov adsorption ntawm cellulose ether thiab ettringite tuaj yeem tsis quav ntsej, thiab hydration ntawm sulfoaluminate yog ceev heev, yog li ntawd, thaum ntxov ntawm hydration, cellulose ether muaj me ntsis cuam tshuam rau hydration tshav kub tso tus nqi ntawm sulfoaluminate cement. Tab sis mus rau ib lub sij hawm ntawm hydration, vim c2s yuav cais hydrate los tsim Ca (OH) 2 thiab CSH gel, ob hydration khoom yuav ncua los ntawm cellulose ether. Yog li, nws tau pom tias cellulose ether ncua cov dej ntawm sulfoaluminate cement tom qab 2 teev.

4. Cov lus xaus

Nyob rau hauv daim ntawv no, los ntawm isothermal calorimetry test, lub hwj chim txoj cai thiab tsim mechanism ntawm cellulose ether ntawm hydration tshav kub ntawm Portland cement, c3s, c3A, sulfoaluminate cement thiab lwm yam sib txawv Cheebtsam thiab ib tug ore nyob rau hauv 72 h tau muab piv. Lub ntsiab lus xaus yog raws li nram no:

(1) Cellulose ether tuaj yeem txo cov dej kub tso tawm ntawm Portland cement thiab tricalcium silicate, thiab cov nyhuv ntawm kev txo cov dej kub tso tawm ntawm tricalcium silicate tseem ceeb dua; Cov nyhuv ntawm cellulose ether ntawm kev txo cov cua sov tso tawm ntawm sulfoaluminate cement yog qhov tsis muaj zog, tab sis nws muaj qhov tsis muaj zog ntawm kev txhim kho cov cua kub tso tawm ntawm tricalcium aluminate.

(2) cellulose ether yuav adsorbed los ntawm ib co hydration khoom, yog li ncua lub crystallization ntawm hydration cov khoom, cuam tshuam lub tshav kub tso tus nqi ntawm cement hydration. Hom thiab kom muaj nuj nqis ntawm cov khoom hydration sib txawv rau cov khoom sib txawv ntawm cov cement nqi ore, yog li cov nyhuv ntawm cellulose ether ntawm lawv cov dej kub tsis zoo ib yam.